1. Field of the Invention
This invention relates generally to a time base corrector or TBC for correcting jitter or time base fluctuation in color video signals reproduced by a recording and/or reproducing apparatus, such as, a video tape recorder or VTR.
2. Description of the Prior Art
A time base corrector or TBC is known in which incoming composite color video signals are supplied to an analog-to-digital or A/D converter to be converted to a digital color signal which is to be temporarily stored in a memory. Write clock and write start pulses are generated in synchronism with horizontal sync signals separated from the incoming composite color video signals and are employed to control the sampling of the latter by the A/D converter and the writing of the resulting digital color signal in the memory. Read clock and read start pulses are generated on the basis of reference burst signals and reference sync signals separated from reference video signals applied to the TBC, and such read clock and read start pulses control the reading out of the temporarily stored color video signals from the memory to a digital-to-analog or D/A converter, whereupon added sync and sub-carrier or burst signals are inserted in the resulting analog color video signal. In the known TBC, a synchronous circuit is provided by which the read start pulses produced from the added sync signals will occur in a predetermined synchronized relationship with the added sub-carrier or color burst signals. Moreover, the known TBC has phase shifters which are controllable to shift the phase of the burst signal of the output of the TBC, and further to shift the phases of the sub-carrier and sync signals of the output of the TBC relative to the sub-carrier and sync signals of the reference video signals. However, when these phase shifts are effected, the timing of the read start pulses relative to the added sync signals is changed with the result that the image provided on the screen of a CRT or monitor by the output of the TBC is shifted transversely.